Physics
The fundamental scientific principle in the operation of battery is

Oxidation-reduction
Dialysis
Acid-base interaction
Dissociation of electrolytes

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Physics
On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because:

density of mercury is greater than that of water.
cohesion of mercury is greater than its adhesion with glass.
cohesion of water is greater than its adhesion with glass.
mercury is a metal.

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